NUTRITION
All living things need food;
-provide energy for vital activities
-growth (provides substances for making new cells)
-replacement of worn and damaged tissues
-maintain health (prevent deficiency diseases).

Food:-Organic and inorganic
Classes:- fats, carbohydrates, proteins, vitamins, dietary fibre =organic food
water and mineral salts = inorganic food

CARBOHYDRATES [C,H,O (1:2:1) (glucose/fructose = C₆H₁₂O₆)]
-Rice, potatoes, wheat, cereal grains, sugars (sucrose), etc.
-sugars - simple/monosaccharides e.g. glucose, fructose, galactose
complex/disaccharides e.g. sucrose, lactose, maltose
Reducing sugars-e.g. glucose, maltose- produce orange/brick-red precipitate when boiled w/
Benedict/Fehling's solution.
polysaccharides e.g. Starch, cellulose, glycogen, etc.
(large complex)
- oxidised for energy for active transport, synthesis of macromolecules, cell division, muscle contraction, etc.
-cheapest source of energy- 1 gram 16/17 kilo-joules of energy. Measure w/ Bomb/Food Calorimeter
(food taken in: 1st carbohydrates, then fats, then proteins)
-Digested-Mouth and small intestines, absorbed as glucose

FATS AND OILS / (LIPIDS) (C,H,O more C + H molecules than O)
-animal foods-rich in saturated fats and cholesterol, plant sources (sunflower and soya), rich in unsaturated fats.
Functions:
-form cell membrane in cells
-oxidised in respiration, 1 gram gives 39 kilo-joules
-insulation + protection-stored under skin for insulation and protection of internal organs
-solvent of fat-soluble vitamins A, D ,E, K
-restricts water loss from skin surface-sebum produced by sebaceous glands in skin reduce evaporation rate of water
-Digested-small intestines, absorbed as fatty acids and glycerol.

PROTEINS (C, H, O, N sometimes P, S)
-milk, dairy products(cheese), eggs, meat, peas, beans
-simpler units-amino acids. Different amino acids linked together form polypeptide chains-protein molecule
Function:
-synthesis of protoplasm, for growth and repair of worn-out body cells.
-metabolism-act as enzymes, which control chemical processes.
-act as hormones which control many important functions in the body.
-building blocks for growth and repair of many body tissues (myosin in muscle, collagen in connective tissues)
-act as transport systems (haemoglobin)
-act as antibodies.
-Not used under any circumstance used for respiration, 1 gram gives 17 kilo-joules.
Deaminated: excess proteins broken down in liver to urea, less harmful substance excreted in urine, + carbohydrates.
-Deficiency-poor growth. Severe deficiency-kwashiorkor-mental and physical development slowed down. Swollen abdomen due to insufficient blood protein to be able to reclaim water from the tissues and to an enlarged liver. Skin cracks and becomes scaly. If shortage of energy food marasmus (general wasting of all body tissues and body becomes very thin and wrinkled) may occur.
-Digested-stomach, absorbed as amino acids.

VITAMINS
-required in small amounts to use other dietary components.
-Organic group w/ special features:
-not digested or broken down for energy.
-not built into any body structures.
-essential in small quantities for normal health and to prevent deficiency diseases.
-needed in chemical reactions in cells, associates w/ enzymes.
-Fat-soluble vitamins can be stored in the body, but water-soluble vitamins can't.
-Water-soluble vitamins present in certain fruits and vegetables.

Vitamin B complex: consists of B1, B2, B7, B12
Important for respiration and healthy nervous system.
Deficiency diseases:B1-Beri-beriB2-dermatitisB7-pellagra (nervous system disorder)
B12-pernicious anaemia (poor amount of haemoglobin)

Vitamin C- Ascorbic Acid (Water soluble)
-Easily destroyed by heat-in cooking and canning
-Richest sources-fresh citrus fruits-papaya, tomatoes, fresh green vegetables, blackcurrant juices
-Needed for formation and repair of tissues (e.g. skin, teeth and bones)
-Deficiency disease-scurvy-loosening of teeth and swollen, bleeding gums; haemorrhage in muscle and skin; wound bleed freely (difficult healing); painful swelling of joints; production of some structural tissues inhibited; skin flaky
-Very low levels of vitamin C may cause immune system to work less efficiently

Vitamins D- Calciferol ('co-brothers' w/ calcium, both work in the presence of each other)
-Fat soluble vitamin, relatively resistant to heat and oxidation.
-Rich sources-cod-liver oil, fish, egg yolk, milk, formed from ergosterol (in skin) when exposed to ultra-violet light.
-Promotes absorption of calcium and phosphorous compounds used in formation of teeth and bones.
-Slight deficiency in growing children-tooth decay
-Severe deficiency rickets (poor teeth and bone formation. bow legs and knock knees) adults-osteoporosis (leads to easy fractures and poor healing of bones). [Vit. K-Deficiency disease-rickets children-bow legs]
-Deficiency in adults-osteomalacia-softening of bones (frequent fractures)
-Excessive doses result in demineralisation of bones w/ multiple fractures and wipe-spread calcification (hardening of organs, can't perform function) of soft tissues, including kidneys and lungs.

MINERAL SALTS (mineral salts and vitamins-protective foods, from deficiency diseases)
-Inorganic substances-don't provide energy. Important in formation of more complex organic molecules.
-available from protein, carbohydrate and lipid molecules-C, H, O, N, P, S.
-macronutrients (needed in large amounts) + micronutrients
-Usually ingested w/ other foods, supplements may be necessary (iron tablets following menstruation).

CALCIUM
-Rich sources-cereals, green vegetables, milk, eggs, fruit, dairy products.
-children-about 1g, adults-slightly less, pregnancy: more and lactation[breast feeding (milk contains-iron, calcium)].
-For formation of bones & teeth, normal functioning of muscles, transmission of nerve impulses.
Severe deficiency-rickets-poor development of bones
[children-bow legs, adults osteoporosis (leads to easy fractures and poor healing of bones)]
-Present in blood plasma. Important in blood clotting. (Vit. K also important)

IRON haemophilia- no blood clotting
-For haemoglobin formation. Rich sources-liver, red meat, bread, eggs, flour and green vegetables
-Adults-15 milligrams a day (women need more-iron lost in menstruation)
Deficiency disease-nutritional anaemia-red blood cells > smaller and fewer [carry less oxygen(poor oxygen transport)]. Red blood cells-limited. Energy from aerobic respiration-reduced. Oxygen capacity-reduced. and very tired.
-Constituent of pigment myoglobin [causes muscle to be red, oxygen reserve for muscle contraction] in muscles.
-Needed to activate certain respiratory enzymes.

WATER
-65%-70% of human body.
-Essential in various chemical reactions; hydrolysis reactions such as digestion, to maintain the body temperature, needed in photosynthesis, removal of waste materials, as solvent, transport medium, substrate in digestive reactions and for lubrication (in tears).
-Require 2-3dm3-from drinks and liquid foods.

ROUGHAGE (Dietary fibre-found in plants)
-Essential, but not absorbed or digested.
-Mainly cellulose (plant cells), don't have enzyme cellulase to digest it > egested [non metabolic food substance/ indigestible food substances + bacteria got rid of].
-Promotes peristalsis-a series of muscular movement of alimentary canal. It enables food to be easily digested and move food along alimentary canal.
-Lack of it leads to constipation (which leads to colon cancer and piles) - faeces, hard + dry and difficult to be egested.
-Sources-fresh fruits and vegetables, wholemeal bread, cereals.
-Regular exercise promotes peristalsis and drinking sufficient water helps to prevent constipation.
-May provide some energy but mainly-aids faeces formation and prevent constipation

ANIMAL NUTRITION
Balanced diet-a diet of the right amounts of carbohydrates, fats, proteins, minerals, water, vitamins and roughage to meet daily requirements of body.
A balanced diet-provides all dietary requirements in correct proportions (ideally- 1/7 fat, 1/7 protein, 5/7carbohydrate).
Depends on age, sex, life-style activities, climatic factors, etc.
-An adequate diet-provides sufficient energy for the performance of metabolic work [ 'energy' could be in any form]
Basal(Basic/Fundamental) Metabolism = minimum amount of energy needed to carry out vital activities of body
Minerals, water and vitamins, enough proteins needed for tissue growth & repair and to prevent deficiency diseases.

-Malnutrition-occurs when diet not appropriate to a person's need (diet-not balanced)
-Undernutrition-Common in under-developed/developing countries. Also due to natural disasters.
Deficiencies occur; Vit. A-Xerophthalmia(cornea hardening and flaking) or night blindness(poor production of visual
pigment), Iron-Anaemia, Vit.C-Scurvy, Protein-kwashiorkor, Calcium or Vit. D-rickets
-Overnutrition-Common in developed countries (Bad nutrition). Diet-more than adequate
Excess food stored as fat, leads to obesity. May cause health problems-heart diseases, kidney failure, diabetes, etc.
-Rich in refined sugar-tooth decay
-High in saturated fats and cholesterol-may cause heart disease
-High in salt-may cause blood pressure to rise, which may cause disorder in circulation.
-Low in dietary fibre-constipation and colon cancer (faeces remains in gut for too long > infects gut muscle)
-Too high in energy content-may cause obesity (excess energy stored in unlimited amounts of fat > joint damage,
increase risk of heart diseases, circulatory diseases, diabetes, infections of lungs as breathing is difficult)

-Anorexia:-eating disorder, where food intake doesn't meet body's demand. Often caused by peer group of fashion pressure. Effects similar to marasmus. Muscles wasted (used for energy), growth and sexual developments limited, metabolic rate and blood pressure decrease, depression and anxiety increase.

FOOD TESTS (Biochemical tests)
(All tests should not be boil by heating directly, but by using a water bath)

Starch:- (can be tested in colloidal suspension or solid form)
-Add 3-4 drops of iodine or potassium iodide > dark blue

Reducing sugars:-
-Add equal amount of Benedict's reagent, shake > gently boilInitial blue > green > yellowish > brick-red/orange
-Add 1cm3 each of Fehling's solution A and B to 2cm3 reducing sugar Green > yellow > brick-red/(orange)


Non-reducing sugars:-
1Do reducing sugar test > negative
2Add dilute HCl, to a new sample > boil for 1 min. Neutralise w/ NaOH or sodium hydrogencarbonate (powder)
Check w/ pH paper
3Repeat reducing sugar test w/ solution (boiled w/ HCl and then neutralise) > positive
(Boiled w/ HCl to hydrolyse it to monosaccharide constituents)

Test for lipids:-
-Add equal amount of ethanol(ethyl alcohol) > shake vigorously until fat/oil dissolves > add equal amount of water (cold) > white cloudy emulsion
-Add equal amounts for water and oil > few drops of SudanIII > oil layer, stained red

Test for proteins:-
-Add Milon's reagent(poisonous) > boil; white precipitate > red/salmon pink.
-Add Biuret reagent (5% K hydroxide/NaOH and 1%CuSO) > shake > mauve, purple/violet

Test for Vitamin C:-
-Add DCPIP (dichloro phenolindolphenol) to 0.1% ascorbic acid > stir gently; blue colour dye fades > colourless sol. [Ascorbic acid-strong reducing agent, reduces DCPIP (a blue dye)]


ANIMAL NUTRITION
STRUCTURE OF ALIMENTARY CANAL (GUTS)
-Food moved through alimentary canal by peristalsis-repeated contraction and relaxation of muscle layers in gut wall

MOUTH
tongue-muscular organ used for; chewing + swallowing, tasting, speech
teeth:-incisors, canines, premolars, molars
-break down food > smaller pieces; increase surface area (for enzymes), facilitate easy swallowing
salivary glands:-sub-mandibular, sub-lingual,parotid glands [1-1.5l of saliva per day (adult)]
saliva, function;-enzyme(amylase), digest cooked starch
-lubricates food > easy swallowing
-moistens mouth & taste buds, prevent drying up
-cleanse food particles trapped between teeth
-alkaline, for enzyme reaction
DIGESTION IN MOUTH
-Food ingested, masticated by teeth > increase surface area.
-Salivary amylase (ptyalin); cooked starch > maltose (denatured in stomach, pH too high) [3-5% starch digested]
-Tongue rolls food into a round ball (food bolus), which is swallowed

OESOPHAGUS

-Tubular organ, composed of muscle and lined by mucous membrane [25cm long. narrowest part of gut]
-Moves food to stomach by peristalsis

STOMACH

-2 main functions;-stores swallowed food (~4h), food: churned > slowly released small intestines by pyloric sphincter
-digests proteins
DIGESTION IN STOMACH
-Gastric juice secreted by gastric glands
Contains:i)enzymes -pepsinogen and prorennin ii)hydrochloric acid iii)water, mucus, salt
-When react w/ HCl; Pepsinogen->active pepsin,digests proteins-> peptones/peptides
Prorennin->active rennin,digest caseinogen (in milk)-> insoluble casein (protein)
-Pepsin loses proteplytic (protein splitting) activity when pH 7
-Water, solvent and for hydrolysis (split large food molecules to smaller ones)
-Mucus, prevents action of gastric juice (autolysis) on stomach walls, also lubricates food movement
-HCl: mild antiseptic, kills bacteria in food, acidifies food for pepsin action
-Food mixed w/ gastric juice by rhythmic contractions. Release by pyloric sphincter in form of (semi-liquid), chyme


SMALL INTESTINES (~6.4m)
-3 parts;-duodenumjejunumileum
-liver and pancreas joined to duodenum by ducts (bile and pancreatic ducts)
-made of 3 layers of muscle; longitudinal and circular
DIGESTION IN THE SMALL INTESTINES
Bile
-Liquid, secreted by liver through bile duct to small intestines
-2 constituents; bile salt and bile pigment
-Bile pigments-derived from haemoglobin of broken down red blood cells
-Bile salts-important for digestion and absorption of fats.
lowers surface tension of fat globules, fat globules emulsified (broken down) to smaller globules
suspended in water, forms emulsion. (increase surface area of globules for enzyme action)
-Bile also neutralizes acid chyme (sodium hydrogen carbonate in bile)
-Water in bile-solvent and hydrolysis
Small Intestines
-3 fluids secreted; bile juiceintestinal juicepancreatic juice
-All alkaline, neutralize acidic chyme (gastric juice), suitable pH for enzymes in intestinal and pancreatic juice.
Pancreatic Juice
-Produced by pancreas, secreted through pancreatic duct to duodenum
-Contains sodium hydrogen carbonate, neutralizes chyme, and for proper pH
-3 enzymes secreted;
trypsin, proteins > peptones
lipase, fat > fatty acids + glycerols
pancreatic amylase, uncooked starch > maltose

Intestinal Juice(succus entericus)
-Secreted by intestinal gland cells in walls of jejunum and ileum. contains water, sodium hydrogen carbonate, mucus
-5 enzymes;
sodium hydrogen carbonate- inactive trypsin > active trypsin (proteins > peptones)
erepsin, peptones > amino acids
lipase, fats > fatty acids + glycerols
maltase, maltose > glucose
sucrase, sucrose > glucose + fructose
lactase, lactose > glucose + galactose

Small intestines good for absorbing;-long, large surface area for absorption
-surface area increased w/ finger-like villi
-epithelium of villi very thin, fast diffusion
-rich supply of blood capillaries in villi to carry away absorbed food

LARGE INTESTINES (~ 1.5m, inverted U-shaped)
-3 parts;caecum & appendix
colon : ascending, transverse and descending colon
rectum & anus
-Digestion completed before large intestines and most nutrients already absorbed
-reabsorb water and minerals from undigested food

Functions Of Large Intestines
-Function;
absorption- water + mineral salts (85%, 15%-villi and stomach), contents more solid (faeces or stool = semi-solid)
bacterial action-micro organisms (bacteria) in caecum break down indigestible material > synthesize vitamins (K)
secretion-secretes mucus, lubricant for passage of faeces through rectum and anus
defaecation (egestion)-faeces, stored in a sac, rectum emptied through anal canal
Food:
-ingested: taken into the body
-masticated: physically broken down by chewing and breaking down into smaller pieces.
-engulfed: swallowing food bolus
-digested: broken down or hydrolyzed into smaller components
-absorbed: taken in by villi in small intestines, for various purposes.
-assimilated: used for metabolic reactions
-egested: waste products removed from the body

ABSORPTION
-Digested food taken into body's system by villi in small intestines (small intestines, folded, and lined w/ mucous membrane, increase surface area. Folds studded w/ figure-like villi)
-Villi, covered by epithelium (one cell thick), and has 3 vessels;
a artery-breaks up into capillary network lying closer under the surface of the villus
a vein-blood from capillaries carried by vein to liver (hepatic portal vein)
lacteal-the central lymph vessel, drains its contents to lymphatic system
Final products;
carbohydrates glucose
protein amino acids
fats fatty acids and glycerol

Glucose, amino acids, fatty acids and glycerol absorbed through the surface of these villi by dialysis
glucose and amino acids absorbed into the capillaries and transported to liver via portal vein
fatty acids and glycerols enter the lacteal and carried away in lymph vessel, to thoracic duct

FUNCTIONS OF LIVER
-deaminate (converts excess amino acids to urea and carbohydrates)
-controls sugar (glucose) level in blood
-stores carbohydrates as glycogen (polysaccharide)
-makes bile (greenish yellow, alkaline, has bile salts, stored in gall bladder
-breaks down red blood cells (life;3-4 months), stores the iron (a lot of haemoglobin which forms bile
pigment) and excretes remains of bile pigment
-breaks down harmful toxic substances [alcohol, drugs, hydrogen peroxide (H₂O₂, produced in plants
and animals, broken down by catalase, to H₂O & O)]
-stores vitamins A and D
-makes cholesterol (needed to make and repair cell membranes)
-produces heat (many metabolic reactions, in liver cells), distributed by blood system





TEETH IN MAMMALS
Mammals; 4 different teeth, adapted to function
Incisors-front of mouth (edges-flat and sharp) [cuts + bites food]
Canines-sharp ends and large, deeply embedded roots [tears food]
Premolars- 2 cusps + 1/2 roots. [tearing + grinding food]
Molars-4/5 cusps [chews + grinds (crushing) food](Premolars + molars = cheek teeth)

STRUCTURE OF TEETH
Externally divided into crown and root
Crown-above the gum. Cheek teeth have cusps
Root-normally buried in socket in jaw bone
Internally; crown-made of a thin layer of enamel (extremely hard)
beneath enamel = dentine (ivory-like)(calcium phosphate make enamel & dentine hard)
soft area in centre of dentine= pulp cavity (contains small blood vessels and nerves)
root- cement (hard material), outside of root, attached to periodontal fibre, which run into jaw bone

periodontal fibres = tough fibres (hold tooth in socket. permits very slight movement for cushioning tooth when excessive jarring occurs when it hits something hard)

Milk teeth and permanent teeth
Each mammal-2 sets of teeth in a lifetime; milk teeth:-when young (usually completed at end of third year)
permanent teeth:-replaces milk teeth from sixth year onwards

DENTAL FORMULAE
Dentition-number + arrangement of teeth in skull of an animal. [variesssshown by a dental formula (shows half skull)]
Man
i-incisors c-canines pm-premolars m-molars


TEETH AND DIET
Dentition closely related to diet
Man-omnivorousMilk dentition i 2/2 c 1/1 pm 2/2
Permanent dentition i 2/2 c 1/1 pm 2/2 m 3/3
Lateral movement of jaw present i-chisel-shapedc-about same size as incisors pm+m-small cusps on surface

Rabbit-herbivorous
Permanent dentition i 2/1 c 0/0 pm 3/2 m 3/3
Roots-openDiastema and lateral movement of jaw are present
(in herbivores, basal part of pulp cavity remains open throughout life so tooth grows continuously as there is a constant supply of food. This avoids worn out and damaged teeth.)

Sheep/Goat
Permanent dentition i 0/3 c 0/1 pm 3/3 m 3/3
Roots-openDiastema and lateral movement of jaw are present
i + c -sharped edged, no upper incisors, lower ones bite against horny pad on upper jaw
pm + m-flat surface, ridges of enamel

Diastema-gap between pm & c -place where canines suppose to be -enables herbivores to manipulate tongue freely

Dog
Permanent dentition i 3/3 c 1/1 pm 4/4 m 2/3
Roots-closed
Carnassials present [large teeth in carnivores (last upper premolars and first lower molars) w/ sharp points and flattened surface adapted for shearing and chewing food]
i-sharp, pointedc-long, pointedpm+m-sharp pointed edges on surface

In mammals, particularly those which eat harsh vegetation, roots widely open tooth continuously grows.

DENTAL DISEASE
-Dental disease-result of bacteria action on teeth. Mouth has many bacteria, some pathogenic
-Many species of bacteria harmful if allowed to accumulate in between teeth or in plaque that can build up on teeth
-Plaque; formed from mixture of food debris, saliva + bacteria, which undisturbed progressively hardens + attaches to tooth. Plaque may harbour harmful micro-organisms

Periodontal disease: bacteria that feed on gum tissue > gum inflammation and bleeding as they feed > bad breath, receding of gums, leading to exposure of cement. Gum tissue > white + dead as bacteria destroy periodontal fibres > tooth loose > falls out. Minimized by brushing and flossing teeth to remove all plaque

Dental caries/decay: bacteria converts sugar to organic acids > erode enamel. Decay faster in dentine. Pulp cavity attacked > severe toothache (caused by prolonged presence of sugar in mouth) Minimized by avoiding sweet food and drinks at frequent intervals, eating hard fibrous food which removes plaque and prevents decay, brushing teeth w/ fluoride toothpaste, drinking water w/ fluoride

DENTAL CARE
-not eating between meals; reduces periods when teeth surface strongly acidic
-avoid sugary snacks, sweets; quickly converted to acids > dental caries
-eatt high fibre diet + lightly cooked wholefoods; mastication of these foods promotes stronger teeth + healthier gums
-regular, careful brushing of teeth; remove debris, prevent plaque build-up, allow free flow of saliva (neutralizing antibacterial)
-floss teeth, remove plaque on and in between teeth
-regular check-ups + treatments
-intake on fluoride; helps teeth mineralisation, increases enamel's resistance to bacteria attack (dental caries)


MINERAL NUTRITION
-Minerals
- absorbed by osmosis, in water (diffusion and active transport)
- needed for proper growth
- continuously absorbed by roots, should be supplemented w/ organic (humus, night soil, prawn dust) and inorganic (chemicals, ammonium nitrates and sulphates) fertilizers. Erosion depletes minerals in soil
-Micronutrients / trace nutrients-required in small amounts (Cu, Zn, Fe, Mg)
-Macronutrients -required in large amounts (N, P, K)
-If plants grown continuously in soil, minerals (nitrates, phosphates) depleted, supplement needed.
Nitrogen in soil, constant, due to nitrogen fixation and nitrification by soil bacteria (Nitrogen cycle)

NITROGEN
-enters in the form of nitrate ions and ammonia, absorbed through soil
-for formation of proteins, protoplasm, enzymes, nucleic acids and chlorophylls
-deficiency = stunted growth fewer, smaller, pale green leaves, seedling usually withers and dies

MAGNESIUM
-enters in form of ions along w/ other chemicals
-it is a constituent of chlorophyll
-deficiency = lack of chlorophyll, chlorosis of leaves, leaves small, yellow

CHEMICAL FERTILIZERS
Disadvantages; -If not washed from edible plants, cause sickness
-long term effect; soil: loss of organic humus, deterioration of soil crumbs , oxygen content
-Eutrophication-unabsorbed minerals, esp. nitrates > washed by rain > drained into rivers and lakes
Soil bed rich in minerals > stimulate excessive growth of planktons > grow quickly > die > decompose
-excessive use > destroy crumb structure > soil dry and powdery > blown away by wind > top soil lost
-on agricultural land; increase use reduces species diversity
-ammonium nitrates can break down to form ammonia > released into air > increases sulphate
deposition rate > soil acidity increases
Advantages;-provides correct nutrients needed by plant
-produce less amount of leached nitrates then organic manures

ORGANIC MANURE
Advantages; -improves soil crumb structure and oxygen + water retention
-provides nutrients for plant growth
Disadvantages; -more likely to produce large quantities of leached nitrates
-doesn't provide correct nutrients like chemical fertilizers

HOW TO REDUCE PROBLEMS CAUSED BY EXCESS NITRATES IN SOIL AND WATER
-avoid ploughing up old grassland
-don't apply excessive organic manure, more likely to produce more leached nitrates
-leave a strip on 10m wide next to water courses, not used for growing
-before applying inorganic fertilizers, measure amount of nitrates in soil > calculate & apply ~ amount needed by plant
-apply fertilizers when crop actively growing, taken in quickly
-don't leave land bare for nitrates are more easily leached from land

PLANT / AUTOTROPHIC NUTRITION
-Green plants convert solar energy to chemical energy, w/ help from CO₂, H₂O, chlorophyll and sunlight
-Green plants=producers (of food+O₂, vital to all aerobic organisms)
-Dicotyledon leaf;
large surface area-more absorption of sunlight and CO₂
thin-CO₂ diffuse faster
large intercellular space-free movement of gases (CO₂,O₂)
covered by waxy cuticle-reflects light, reduce evaporation
many stomata in lower epidermis-diffusion of CO₂ and O₂ in and out of the leaf
many chloroplasts in palisade mesophyll cells-main site for photosynthesis, more absorption of sunlight
network of veins-contain xylem and phloem
contains starch-reserve food substance, at night converted to glucose, sucrose for respiration (energy) + make fats
& amino acids which can be stored
-Leaves of plant arranged so don't shade each other-max. sunlight
-Petiole of leaf holds leaf in a way to obtain max. sunlight

PHOTOSYNTHESIS
-takes place in cell organelles, chloroplasts, which contain chlorophyll
-2 types; light reaction / light dependant reaction and dark reaction / light independent reaction
-Light reaction: light trapped by chlorophyll in chloroplast (grana). H₂O split to hydrogen (H⁺) and hydroxil (OH^-) ions
H₂O → H⁺ & OH^-
hydroxil ions; combine > H₂O, w/ release of O₂
hydrogen ions used up to make energy rich molecules (ATP, NADPH₂-Nicatinamide adenine dinucleotide phosphate)
-Dark reaction: Stroma in chloroplasts-CO₂ reduced to glucose (6 carbon sugar-hexose) Energy used and enzyme dependant (photosynthesis varies at temp.)
Photosynthesis
6 CO₂ + 12 H₂O →(chlorophyll + sunlight)→ C₆H₁₂O₆ (glucose) + 6 O₂ + 6 H₂O
-Importance;
-animals directly or indirectly dependant on plants for food (they make carbohydrates, fats, proteins and other organic compounds)
-produce O₂ and use CO₂
-through photosynthesis, solar energy converted to energy stored in fossil fuels (coal, derived from trees)
-Limiting factor-the factor which is nearest to its min. value and limits rate of the process,
photosynthesis (in photosynthesis-CO₂, light intensity + temp.)

Transport in Plants
Support, Movement and Locomotion
Transport system in man-circulatory system
Respiration
Excretion
Homeostasis
The Eye
Nervous System
Chemical Control of Plant Growth
The Use and Abuse of Drugs
Diversity of Organisms
Nutrient cycles and Ecology
Parasitism
The Human Impact on the Environment
Reproduction in plants
Sexual reproduction in animals
Genetics
Cell Structure and Organisation
Enzymes

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